The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. Such scaling down has also increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed.
With small feature sizes in advanced technology nodes, lithography patterning faces more challenges. For example, overlay error needs to much smaller since feature size is reduced. On the other hand, lithography technology uses a radiation beam of high energy photons, such as deep ultraviolet (DUV) or extreme ultraviolet (EUV), since high energy photons have short wavelength and high resolution that enable formation of small size features.